The specular gloss, respectively shininess, of polished grain or grains, e.g. rice, is an important quality parameter in the grain milling industry. The obtained surface or the luster of the surface of the grain is an expression of the achieved quality of the polishing. The state of the art assessment of the gloss is manually done based on visual measured and therefore subjective to the perception of the assessor. Furthermore a manual assessment of the gloss can be done only batch-wise, in particular random samples, resulting in a not reproducible assessment of the gloss for industrial processed grains.
Generally, it is difficult to judge the quality of grain especially rice which is available in number of varieties which are different in quality, assessed e.g. as high grade or low grade quality. The assessment of quality, e.g. gloss of rice, is determined based on personal judgment which requires at least two samples to be compared. In the absence of any methods that are supported from a scientific view point, the rice thus produced has often tended to be irregular in quality and this has often been the subject of concern.
Gloss is an optical property describing the ability of a surface to reflect light into the specular direction. The factors that affect gloss are the refractive index of the material, the angle of incident light and the surface topography.
Gloss is one of the factors that describe the visual appearance of grains. Grains with smooth surfaces appear glossy. Grains with rough surfaces reflect less specular light and appear dull. Therefore measuring the gloss properties of grains is a method to evaluate the surface quality gloss of the grains.
The appearance of gloss depends on a number of parameters which include the illumination angle, surface condition and observer characteristics.
It is well known to use a gloss meter or similar device for measurement of shininess, which are ideally used for paper, paint and plastics. These meters are typically suited for products with flat surfaces.
In the absence of any defined standards and methods that are supported from a scientific view point, the grain, especially rice, thus produced has often tended to be irregular in quality and this has often been the subject of concern.
It is therefore a need in the art for a method for determining the gloss of grain, especially rice, which can serve as a basis for an objective assessment especially of the quality of polished rice grains.
Furthermore modern plants, in particular rice mills, processing rice grains in large quantities depend on a continuous monitoring of the grain quality, e.g. gloss of the grain. Furthermore a process control to steer the grain plant depending on grains processed would be beneficial to maximize the economic value of the processed grains.